Plasma processing apparatus and method

Abstract

A plasma processing apparatus includes a worktable in a process chamber to horizontally place a target substrate thereon. A plasma generation space is defined above and around the worktable within the process chamber. The plasma generation space includes a peripheral plasma region and a main plasma region respectively located outside and inside an outer edge of the target substrate placed on the worktable. The apparatus further includes a magnetic field forming mechanism configured to form first, second, and third magnetic fields within the peripheral plasma region. The first magnetic field includes magnetic force lines extending along a vertical first cylindrical plane. The second magnetic field includes magnetic force lines extending along a vertical second cylindrical plane located inside the first cylindrical plane. The third magnetic field includes magnetic force lines extending along vertical radial planes located between the first and second cylindrical planes.

1. A plasma processing apparatus comprising:
 a process chamber configured to reduce a pressure therein; 
 a worktable disposed in the process chamber and configured to place a target substrate thereon in an essentially horizontal state, a plasma generation space being defined above and around the worktable within the process chamber, and the plasma generation space including a peripheral plasma region and a main plasma region respectively located outside and inside an outer edge of the target substrate placed on the worktable; 
 a process gas supply section configured to supply a process gas into the plasma generation space; 
 an electric field forming mechanism configured to form an RF electric field within the plasma generation space; and 
 a magnetic field forming mechanism located above and extending concentrically with the peripheral plasma region, and comprising first N-poles, first S-poles, second N-poles, and second S-poles, which are arrayed in a same horizontal level and face downward above the target substrate such that each of the first N-poles, first S-poles, second N-poles, and second S-poles are oriented vertically so as to extend respective magnetic force lines downward therefrom, 
 wherein the first N-poles and the first S-poles are alternately disposed at intervals in a first annular direction outside the outer edge of the target substrate, while the second N-poles and the second S-poles are alternately disposed at intervals in a second annular direction outside the outer edge of the target substrate and inside the first annular direction, to set the peripheral plasma region to have a magnetic field vertically extending as a curtain surrounding the main plasma region and to set the main plasma region to have substantially no magnetic field, and 
 wherein each set of one of the first N-poles and one of the second S-poles is arrayed substantially in a radial direction, and each set of one of the first S-poles and one of the second N-poles is arrayed substantially in a radial direction. 
 
   
   
     2. The apparatus according to  claim 1 , wherein an upper electrode and a lower electrode functioning as the worktable are disposed in parallel with each other with a gap therebetween within the process chamber; the plasma generation space is defined within a space surrounded by the upper electrode, the lower electrode, and a sidewall of the process chamber; the electric field forming mechanism is configured to apply an RF power across the upper electrode and the lower electrode; and the process gas supply section is configured to supply the process gas between the upper electrode and the lower electrode. 
   
   
     3. The apparatus according to  claim 1 , wherein the magnetic field comprises a first magnetic field formed of magnetic force lines that make U-turns extending through the peripheral plasma region from start positions defined by the first N-poles to end positions defined by the first S-poles. 
   
   
     4. The apparatus according to  claim 3 , wherein the magnetic field comprises a second magnetic field formed of magnetic force lines that make U-turns extending through the peripheral plasma region from start positions defined by the second N-poles to end positions defined by the second S-poles. 
   
   
     5. The apparatus according to  claim 4 , wherein the magnetic field comprises a third magnetic field formed of magnetic force lines that make U-turns extending through the peripheral plasma region from start positions defined by the first and second N poles to end positions defined by the first and second S-poles. 
   
   
     6. The apparatus according to  claim 1 , wherein the magnetic field forming mechanism comprises a plurality of magnets combined to provide the first N-poles, the first S-poles, the second N-poles, and the second S-poles. 
   
   
     7. The apparatus according to  claim 6 , wherein the magnetic field forming mechanism further comprises a yoke disposed in contact with or close to a backside of the magnets reverse to the peripheral plasma region. 
   
   
     8. The apparatus according to  claim 7 , wherein the yoke expands continuously over all the magnets. 
   
   
     9. The apparatus according to  claim 1 , wherein the magnetic field forming mechanism further comprises a rotation mechanism configured to integratedly rotate the first N-poles, the first S-poles, the second N-poles, and the second S-poles in an annular direction. 
   
   
     10. The apparatus according to  claim 1 , wherein the a process gas supply section comprises a showerhead having a plurality of gas delivery holes in a lower surface facing the main plasma region. 
   
   
     11. A plasma etching apparatus comprising:
 a process chamber configured to reduce a pressure therein; 
 a worktable disposed in the process chamber and configured to place a target substrate thereon in an essentially horizontal state, a plasma generation space being defined above and around the worktable within the process chamber, and the plasma generation space including a peripheral plasma region and a main plasma region respectively located outside and inside an outer edge of the target substrate placed on the worktable; 
 a process gas supply section configured to supply an etching gas for etching the target substrate into the plasma generation space, the process gas supply section comprising a showerhead disposed above the worktable in the process chamber and having a plurality of gas delivery holes in a lower surface facing the main plasma region; 
 an electric field forming mechanism comprising a lower electrode combined with the worktable and an upper electrode combined with the showerhead, and configured to apply an RF power across the lower electrode and the upper electrode to form an RF electric field within the plasma generation space; and 
 a magnetic field forming mechanism located above and extending concentrically with the peripheral plasma region, and comprising first N-poles, first S-poles, second N-poles, and second S-poles, which are arrayed in a same horizontal level and face downward above the target substrate such that each of the first N-poles, first S-poles, second N-poles, and second S-poles are oriented vertically so as to extend respective magnetic force lines downward therefrom, 
 wherein the first N-poles and the first S-poles are alternately disposed at intervals in a first annular direction outside the outer edge of the target substrate, while the second N-poles and the second S-poles are alternately disposed at intervals in a second annular direction outside the outer edge of the target substrate and inside the first annular direction, to set the peripheral plasma region to have a magnetic field vertically extending as a curtain surrounding the main plasma region and to set the main plasma region to have substantially no magnetic field, and 
 wherein each set of one of the first N-poles and one of the second S-poles is arrayed substantially in a radial direction, and each set of one of the first S-poles and one of the second N-poles is arrayed substantially in a radial direction. 
 
   
   
     12. The apparatus according to  claim 11 , wherein the magnetic field forming mechanism comprises a plurality of magnets combined to provide the first N- poles, the first S-poles, the second N-poles, and the second S-poles. 
   
   
     13. The apparatus according to  claim 12 , wherein the magnetic field forming mechanism further comprises a yoke disposed in contact with or close to a backside of the magnets reverse to the peripheral plasma region. 
   
   
     14. The apparatus according to  claim 13 , wherein the yoke expands continuously over all the magnets. 
   
   
     15. The apparatus according to  claim 11 , wherein the magnetic field forming mechanism further comprises a rotation mechanism configured to integratedly rotate the first N-poles, the first S-poles, the second N-poles, and the second S-poles in an annular direction.